Dame's Rocket, Hesperis matronalis, is in bloom this time of year. It has lavender, white, or pinkish flowers. Often confused with tall garden phlox, this invasive is a garden escapee. Originally brought to the colonies from Europe, the plant now appears frequently throughout New England. Here in Massachusetts, the planting of it is prohibited. Generally, the plants are biennial producing leaves the first year and flowers the second. They prefer sunny or partly shady areas with moist soil. Luckily, when young, the plants are fairly easy to remove from the soil.
Although invasive, this plant isn't quite so horrible as Rosa multiflora or Oriental Bittersweet. It's not nearly as tenacious and is actually quite nice in small doses. Unfortunately, if given enough time, the plant will take over. I've seen Dame's Rocket growing next to highways, coming up between pavement and concrete steps, and readily growing in abandoned fields. So, if it's appearing in your yard, you may want to pull it as soon as it appears, or perhaps enjoy it until it flowers, then cut it back so it doesn't produce seed.
Recommended Plant: Hemerocallis "Bandit Man."
When this plant was first recommended to me, I read the description and said to myself, "Oh, it's another orange daylily, sounds pretty dull, why is someone recommending it?" The first year I had it in the ground it performed well, flowered, and was fairly unimpressive. Yes, the flowers were nice, but nothing to write home about. The second year, and years beyond, I realized exactly why it was such a great plant. It produces numerous flowers and all of them are large (4-5" across). The red eye zone goes well with the orange tones of the petals. The plant thrives in less than stellar conditions (hot and dry soil to be exact). Because the flowers are numerous and large, they look fantastic even from a distance. Although it only blooms once during the summer, it generates enough flowers so the bloom period is lengthy. It would be an amazing plant to have in a large grouping. In the picture below the colors are a bit washed out due to the bright sunlight. The orange is a tad richer in color and the eye zone more red than orange.